Side doors of vehicles comprise inner and outer door panels and the hardware accessories secured between the panels. More recently, intrusion beams have been positioned between the panels to offer protection from side impacts. Also more recently a modular approach has been taken with respect to the assembly of the door. In a joint proposal by the Budd Company Stamping and Frame Division and ITT Automotive a modular door hardware plate assembly was proposed which is pre-assembled with the hardware and pre-tested before assembly into the door. The heart of the modular assembly proposal is a stamped module plate which purportedly locates and supports all internal door hardware. The stamped plated assembly with components is then assembled to the door. The plate alone, however, is not sufficient to provide protection from side impact.
Another proposal was made jointly by Bayer AG and Dynamit Nobel AG of Germany. The basic features of the modular composite door prototype were an inner steel skeleton structure encapsulated within a polyurethane, and an outer panel made of polyurea.
The skeleton of the inner panel was proposed to be a welded steel frame made of rolled sections and stampings. The skeleton is attached on one side to a hinge plate and on the other to the housing for the latch mechanism. Bent cross-members extend from one side of the skeleton proximate the housing for the latch mechanism to the other side of the skeleton. Braces secure the cross-members. The skeleton does not however provide the primary side impact protection.
It is therefore an object of this invention to provide a structural module for a vehicle door capable of carrying the load of the door, preclude sag, and afford protection to passengers riding in a vehicle from side impact.
Federal Motor Vehicle Safety Standard No. 571.214 specifies door strength requirements which minimize the safety hazard caused by intrusion into the passenger compartment in a side impact accident. This standard specifies 2250 lbs (10000N) as the initial crush resistance for a side door. The initial crush resistance is defined as the average force required to deform the door over the initial 6" (150 mm) of the crush. This crush test is performed by a vertical cylindrical intruder. The load versus displacement curve is plotted while a quasistatic load is applied to the door by the intruder in an inboard direction until the intruder travels 6". The integral of the applied load with respect to the crush distance for 0" to 6" divided by 6 is the average force in pounds required to deflect the door that distance.
As is known, where an intrusion beam is used in a door, a graph plotted of force versus displacement provides generally a characteristic curve. (See FIG. 13A)
The characteristic curve has three distinct sections. The curve begins with a linear slope which has been previously established to be dependent on the geometric bending stiffness of the beams and their end conditions. This is followed by a sharp change in the slope (first peak) which is due to the yielding, or more likely, plastic buckling of the central region of the beam. Finally the curve follows a somewhat lower slope in which post buckling deformations occur. The 6" displacement of the intruder usually includes these three sections. If the test is allowed to continue, the slope of the characteristic curve will change radically toward a steeper curve and ends when the beam fails. This final slope is mainly caused by the membrane stiffness of the tubes. FIG. 14 illustrates the deflection of a single tube when deformed by force F and in respect of which the curve in FIG. 13 applies.
It is a further object of the invention to provide an improved structural module which is easy to assemble and mount. Particularly in the past it has been difficult to mount hardware, raise and lower the window in the door, and still provide protection from side impact.
Further and other objects of the invention will be realized by those skilled in the art from the following summary of the invention and detailed description of an embodiment thereof.